1. Field of the Invention
The invention pertains to backflow prevention devices for use in drains and in particular soil pipes. More particularly the invention pertains to an automatically activated water backflow prevention device having one end disposed in a wax or elastomeric sealing ring of a water closet and the other end disposed in a soil pipe. The end disposed in the soil pipe has a cam shaped end for accommodating a closure member having a substantially parabolic shaped upper surface and a substantially parabolic shaped lower surface with an elastomeric sealing member disposed between the cam shaped end and the closure member so that the closure member in the open position has a low profile by substantially conforming to the inside cylindrical shape of the waste pipe and in the closed position seals the cam shaped end of the backflow prevention device.
2. Description of the Related Art Including in the U.S. Information Disclosed Under 37 CFR 1.97 and 1.98
One of the biggest problems is the backflow of sewage from sewer waste pipes through the water closet in homes, apartments and businesses, particularly in low lying areas. The problem of backflow of sewer water through sewer pipes is generally caused by excessive rain fall or incapacity of the sewer system to handle the amount of rainwater or sewage that is dumped into the sewage processing plants. As a result backflow pressure builds up until pressure in the lines exceeds the capacity of the system causing sewage or backup flows in homes and business in lower lying areas. In the meantime those homes and businesses at higher elevations continually empty more water and sewage into the entire system causing further backflow pressure causing a further backflow of sewage in which the lowest areas receive the most sewage and backflow pressure which when unchecked backflows into successively higher areas.
The problem of backflow sewage in sewage systems into homes, apartments and businesses is particularly aggravated by the fact that many sewer systems are old and do not have sufficient capacity and older developments are usually located in lower areas while more recent construction occurs on higher ground causing an overall increase in backflow pressure in the older lower lying areas. This problem of old sewer systems and inadequate capacity is further compounded by longer sewer lines that are stretched to reach more remote outlying areas from the treatment plant which puts further demands on the system which becomes overwhelmed during periods of heavy rainfall and during periods when the water saturation in the soil is particularly high.
A number of prior art efforts have been made to provide a toilet backflow preventing system and valve such as represented by Hodge U.S. Pat. No. 4,637,079. In this prior art a toilet backflow preventing valve is conveniently provided between the soil pipe mounting flange and the drain horn of the toilet. The valve of Hodge U.S. Pat. No. 4,637,079 is manually activated by pushing or pulling a rod that is connected to a sliding valve to open and close the connection between the soil pipe drain and the toilet bowl.
The problem with prior art such as Hodge '079 is that a person needs to be present to observe the problem and then close the valve to prevent the backflow of sewage or remember to open the valve before flushing the toilet. Many times sewage backflow occurs when people are either not in their homes or in their businesses or when they are asleep and the sewage system becomes overwhelmed. As a result an inexpensive system is needed that automatically closes a valve upon detecting a backflow pressure and which otherwise remains open without interfering with the normal operation of the water closet. It would be further advantageous to dispose such an automatic check valve between the drain horn of the toilet and the soil pipe.
Other prior art such as Hatfield U.S. Publication Nos. 2005/0188452 and U.S. 2004/0172745 provides a backflow preventing attachment for toilets which remains in the closed position in normal operation and opens whenever the toilet is flushed. The system of Hatfield utilizes a duckbill shaped insert composed of two halves which automatically open and close in response to water pressure. Backflow water pressure causes the duckbill system of Hatfield to remain closed while flushing the toilet temporarily opens the duckbill to allow the contents of the toilet to be discharged into the sewage system.
The Hatfield system provides an advantage over the Hodge U.S. Pat. No. 4,637,079 prior art by providing an automatic system for solving the problem except where matter such as toilet paper becomes lodged on one portion of the duckbill or where waste builds up along the surface of the duckbill eventually preventing complete closure and sealing of the duckbill. A fully automatic system such as Hatfield has a further limitation in that the duckbill portions of the valve can not fully open in such a manner as to be completely out of the way of material in the toilet from emptying into the soil pipe. More particularly the elements of the duckbill do not assume a low profile or zero profile to flow of the contents of the toilet into the soil pipe.
There are also numerous examples of other types of inline check valves which are disposed portions of drain pipe such as Floh, et al. U.S. Pat. No. 6,848,471 and Young U.S. Pat. No. 6,199,576. Such backflow preventers are many times expensive to produce and difficult to install as they are disposed in portions of the line not readily accessible. For example Young U.S. Pat. No. 6,199,576 utilizes a bidirectional clean out with a built in backflow preventer having a check valve which allows fluid to flow in only one direction. Young U.S. Pat. No. 6,199,576 utilizes a rod attached to the check valve to lower the check valve into the sewer line through a bidirectional clean out pipe. The check valve in Young U.S. Pat. No. 6,199,576 is automatic but requires the installation of special bidirectional clean out pipes outside of the dwelling, apartment or business and is not conveniently located between the interface between the sewer pipe and toilet.
Huber U.S. Pat. No. 6,085,363 pertains to a water closet fitting with a removable test baffle which test baffle has a concave upper surface and a convex lower surface. The Huber U.S. Pat. No. 6,085,363 provides a removable test baffle to check the integrity of the seal after the water closet drain system has been installed in a permanently set floor such as concrete. After testing for the fluid tightness of the water closet fitting the removable test baffle is removed through an access clean out port in the sewer line. As a result the water closet fitting with test baffle is not a check valve and does not remain in the sewer line to prevent water backup.
Other prior art such as Izzie U.S. Pat. No. 4,482,161 pertains to gaskets disposed between the water closet and the sewer pipe. Izzie U.S. Pat. No. 4,482,161 gasket provides a substitution for the traditional wax ring which is used most commonly in prior art toilet installations. As pointed out in Izzie U.S. Pat. No. 4,482,161 the problem with wax rings is the seal can become broken where the toilet is installed on an uneven floor which allows the seepage and escape of sewer gases from the sewer pipe between the interface between the toilet and the floor. Izzie U.S. Pat. No. 4,482,161 does not have a backflow check valve and unlike the present invention utilizes a reusable gasket of rubber like material for installation of the water closet.
The invention in contrast to all the prior art provides an automatically activated check valve which responds to backflow pressure to close the sewer pipe and can utilize either the traditional wax ring for sealing the interface between the toilet and the sewer pipe or a natural or synthetic elastomeric gasket a combination of a wax ring together with a natural or synthetic elastomeric ring shaped seal for sealing the interface between the sewer pipe, toilet horn and the floor.
The prior art also includes various types of toilet valves that are not particularly relevant to the invention such as rotary gate valves for aircraft vacuum toilet systems such as illustrated by Rosenblatt U.S. Pat. No. 6,325,356. Other prior art also not particularly relevant pertains to inline check valves for pressurized systems such as Floh, et al. U.S. Pat. No. 6,848,471. These and other prior art patents provide for valves in pressurized lines and systems that are complicated in design and expensive to produce and difficult to install.
The invention in contrast pertains to a simple, inexpensive to produce and easy to install device that remains open and assumes a low to zero profile in the axial direction of flow in a sewer pipe and automatically closes upon receiving backwater pressure. The novel backflow preventing valve of the invention utilizes a substantially circular support member terminating in a cam shaped end for accommodating a check valve which has a curved or parabolic shaped upper surface and a curved or parabolic shaped lower surface that is attached to the support member by a hinge and may optionally include a backflow water pressure responsive assist means for assisting in the closure of the check valve in response to backflow water pressure.
As will be recognized by those skilled in the art there is a need for a device which is conveniently installed and automatically activated by backflow water pressure to close the toilet from the sewer line to prevent the backflow of sewage. There is also a need for a device that is simple and inexpensive to produce and easily installed to solve a major problem confronting home owners, apartment owners and businesses in areas that are subject to sewage backflow.
There is also a need for a device that has a low to a zero profile in a sewer pipe and remains open when there is no backflow pressure and effectively closes automatically upon the presence of sewage backflow. There is also a need for a backflow prevention valve that remains open and does not impede the ordinary flow of sewage but which when activated by backflow water pressure automatically closes to prevent the inflow of sewage from a sewage line. These requirements for an efficient automatic backflow prevention system are provided by the invention.